1 ½pounds(680 g)white potatoes - peeled and diced into 2-inch pieces
1 ½pound(680 g)sweet potatoes - peeled and diced into 2-inch pieces
1teaspoonsalt
6tablespoons(84g)butter - divided
⅔cup(162 ⅔g)warmed milk - divided
¼teaspoonfreshly ground pepper
Instructions
Place 1 1/2 pounds white potatoes into the bottom of a saucepan, then 1 1/2 pound sweet potatoes. Add 1 teaspoon salt. Barely cover potatoes with cold water. Bring to a boil, then reduce to simmer until potatoes are fork-tender but not falling apart.
Drain potatoes. Remove sweet potatoes from the pan and place them into another bowl. Place white potatoes back into your original pan and let them dry while you mash the sweet potatoes. For this step, I put on plastic gloves to remove the hot sweet potatoes.
Mash the sweet potatoes your favorite way. (I use a ricer, but a potato masher or portable mixer is also good.)
Start with about 2 tablespoons of the 2/3 cup warmed milk and half of 6 tablespoons butter. Add more milk, if needed, to make potatoes creamy and smooth but not runny. Taste to see if they need more salt. Add freshly ground pepper (1/8 teaspoon)
Repeat steps 3 and 4 with the white potatoes. Again, start with about 2 tablespoons of milk and the remaining butter. Add more milk, as needed, until the consistency matches your sweet potatoes. Taste to see if they need more salt. Add freshly ground pepper (1/8 teaspoon)
Plop mashed sweet potatoes back into the pan with mashed white potatoes. Make a couple of folds with a spoon to barely mix. Move to a serving dish being careful not to mix too much.